Conventionally, for example, Patent Document 1 proposes an optical sensor device including multiple first light receiving elements and a singular second light receiving element having a light receiving area larger than that of each of the first light receiving elements. The multiple first light receiving elements are arranged around the second light receiving element and are different from each other in elevation angle of light to be detected. The second light receiving elements are configured to receive light incident from various directions.
The optical sensor device compares intensities of output signals from the first light receiving elements. In this way, the optical sensor device specifies the first light receiving element, which outputs the most intense output signal, and specifies the angle of the light incident on the light receiving surface of the first light receiving element as specified. In addition, the optical sensor device calculates an irradiance level of light based on the output signals of the second light receiving elements. In this way, the optical sensor device is configured to figure out a directivity characteristics of incident light.
However, in the above-described conventional technique, the light detected with the second light receiving elements includes not only light in one direction specified from the output signals of the respective first light receiving elements but also light at various angles. For this reason, the irradiance levels of light detected with the second light receiving elements depend on the irradiance level at an arbitrary angle. Therefore, there is a concern that a detection accuracy of the directional characteristic may be insufficient.